A spark plug may provide energy to begin combustion within a cylinder of an engine. In particular, a voltage potential may develop across electrodes of a spark plug. If the voltage potential is greater than a threshold, a spark may be created between spark plug electrodes, thereby facilitating ignition of an air-fuel mixture in a cylinder. Ignition of the air-fuel mixture provides engine torque and may result in engine knock. Engine knock may be produced when end gases of a cylinder air-fuel mixture ignite due to increases in temperature and pressure in the cylinder. The ignition of end gas may result in high frequency cylinder pressure oscillations that provide an engine knocking sound. An ignition coil secondary winding may be monitored via ion sensing circuitry to determine if engine knocking is present. However, some higher output ignition coils have higher inductance windings that may cause engine knock sensing to be more challenging. Further, an ion signal may be integrated to estimate engine combustion quality or misfire.
If a conductor is provided between a controller that issues spark timing commands and ignition circuitry for each command signal, a number of conductors in the system may increase rapidly. Further, multiple circuits may have to be supplied to determine spark timing, ignition coil shunting, and ion sensor output. Consequently, it may be difficult and/or less reliable to provide a desired level of ignition system sophistication.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for providing spark to an engine, comprising: receiving input from one or more engine sensors to a controller; and commanding via the controller shunting, charging, and discharging of an ignition coil during a cylinder cycle in response to the input, the commanding accomplished via a single conductor providing electrical communication between the controller and an ignition coil drive circuit.
By providing multiple ignition circuit commands over a single conductor, it may be possible to reduce a number of conductors between a controller and ignition circuitry. The reduced number of conductors may reduce wiring issues and lower system cost. Further, a lower number of conductors within the engine system may improve vehicle reliability. In particular, a single conductor positioned between a controller and an ignition circuit may carry three or more encoded voltage pulses that provide ignition timing, ignition coil shunt timing, and ion signal integration timing. The voltage pulses are carried by the single sole conductor during a cycle of the engine so that ignition, ignition coil shunting, and ion signal integration may be performed during a single cylinder cycle. Further, the pulses may be modified each engine cycle to adjust spark timing, adjust ignition coil shunting timing, and adjust ion signal integration timing.
The present description may provide several advantages. In particular, the approach reduces the number of conductors in an engine system. Further, the approach may improve system reliability by reducing a number of electrical system connections in the system. Further still, the approach may simplify circuitry to decode ignition timing, ignition coil shunting, and ion signal integration because only a single decoding circuit is used to determine ignition system timing signals sent via a controller.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.